home work for science

1General Science 1B
Credit 3
Rev. 5/5/21
NAME:_________________________
CREDIT 3B: MECHANICAL ENERGY
Learning Goals for this Credit
Design an investigation or model using appropriate scientific tools, resources and methods.
Use mathematics to represent physical variables and their relationships to make quantitative predictions and to
solve problems.
Lesson
Title
INTRODUCTION
3.1
Potential and Kinetic Energy
3.2
Conservation of Energy
3.3
Machines
Assignments

 Connect to Essential Question
 Exploration Activity
 Reading and Questions
 Videos (optional)
 Pendulum Simulation
 Review Questions
 Connect to Prior Knowledge
 Exploration Activity
 Reading and Questions
 Videos (optional)
 Skateboard Energy Simulation
 Review Questions
 Connect to Prior Knowledge
 Exploration Activity
 Reading and Questions
 Videos (optional)
 Energy Transfer in a Trebuchet
 Review Questions


PERFORMANCE TASK
QUIZ
Student Support Icons
Title
Icon
Description
Review
Activity
This provides the students with a reminder that they need to answer questions.
Technology
Guides students through the tasks and assignments that require the use of
technology and manipulatives.
Reading
This icon lets the students know they will be completing a reading activity.
Credit Materials



Materials
Pen/Pencil
HMH Physics Textbook
(optional)
Packet



Technology Needs
Internet
Computer
HMH Online Resources
(optional)
2
General Science 1B
Credit 3
NAME:_________________________
CREDIT 3B: INTRODUCTION
Read “What is Mechanical Energy” and watch the video “Types of Energy” below. Then answer the essential
question.
What is Mechanical Energy?
Energy is a concept which connects all of science. Energy
comes from the sun in the form of radiation. Both food and
moving objects have energy. Although it is familiar, energy
is not easy to define. People, places, and things have energy
but the effects of energy can only be seen when something is
happening. Instead of studying all of the possible
interactions, scientists focus on a single small piece called a
system. Within a system, energy is conserved; it is not
created nor destroyed. Energy can be transformed from one
form to another and pass through the system from outside.
Energy is a property of matter. Speed and temperature are
descriptions of the amount of energy in an object. Energy is
also a way to describe the interactions between objects. An
interaction between objects could be how much force is
acting on an object (due to contact or its movement through
a gravitational or electromagnetic field). Or an interaction
could describe how much heat is being transferred from one
object to another (friction and chemical reactions). It is clear
that energy takes many forms.
In this credit you will study mechanical energy, such as the
energies contained in a baseball. These are the energies associated with motion. Mechanical energy can be
divided into two groups. These groups are kinetic energy and potential energy. Kinetic energy is associated
with the motion of mass, and potential energy is associated with the position of mass.
3
General Science 1B
Credit 3
NAME:_________________________
An essential question is something that allows you to explore what the credit is about. Before you answer the
question, examine the diagram below. Watch the video if you feel you need more information. Then, answer
the essential question to the best of your ability. You will revisit it at the end of the credit to see if your answer
has evolved.
Amanda Johnson:

Amanda Johnson: Watch all of this video. It will help
you understand the different types of energy.
Video: Types of Energy (3:22)

“Physics – Energy – Types of Energy” YouTube. expertmathstutor, 7 Jan. 2014.
Energy cannot be created nor destroyed, but it can be made to change form. You may be familiar with many
situations of energy transfer, even if you do not realize it.
Essential Question
What are some examples of energy you come in contact with daily?
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
4
General Science 1B
Credit 3
LESSON 3.1: POTENTIAL AND KINETIC ENERGY
Learning Goals for this Credit
Design an investigation or model using appropriate scientific tools, resources and methods.
Use mathematics to represent physical variables and their relationships to make quantitative predictions and
to solve problems.
Learning Goals for this Lesson
 Identify sources of energy.
 Relate gravitational potential energy and kinetic energy.
Lesson Assignments
 Connect to Prior Knowledge
 Exploration Activity
 Reading and Questions
 Videos (optional)
 Pendulum Simulation
 Review Questions
Engage
Connect to Prior Knowledge
Why is a cell phone more likely to break when dropped from a higher height than a lower one?
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
5
General Science 1B
Credit 3
Explore
Exploration Activity
Energy comes in many forms but is typically placed into two main categories: potential and kinetic. Potential
energy is stored energy, while kinetic energy is the energy of movement.
Potential Energy – Stored energy and energy of position:




Chemical energy is energy stored in the
bonds of atoms and molecules. It is energy
that holds these particles together. The
foods we eat, biomass, petroleum, and
natural gas are examples of this type of
energy.
Elastic energy is energy stored in objects
by the application of a force. Compressed
springs and stretched rubber bands are
examples.
Nuclear energy is stored in the nucleus of
an atom. This energy can be released when
a chemical nucleus is split or combined
with another nucleus.
Gravitational potential energy is the
energy of position or place. A rock resting
at the top of a hill contains this type of
energy.
Kinetic Energy – the energy of motion:





Electrical energy is the movement of
electrons. This type of energy moves
though wires to power your devices and lightning.
Radiant energy travels as electromagnetic waves. Wi-Fi signals, x-rays and visible light are examples.
Thermal energy is the energy of heat. This is caused by the vibration of molecules and can be felt with
any change in temperature.
Motion energy or mechanical energy is the movement of objects from one place to another.
Sound energy is sound waves through a substance, such as air. Anything you can hear is an example of
sound energy.
6
General Science 1B
Credit 3
The Law of Conservation of Energy states that
energy cannot be created nor destroyed.
When we use energy, we do not use it completely –
we just change its form. That is what we mean when
we say we are using energy. We change one form of
energy into another. A car engine burns gasoline,
converting the chemical energy in the gasoline into the
motion energy that makes the car move. Energy can
change form, but the total quantity of energy in the
universe remains the same.
Adapted from “Energy Sources: Introduction to Energy.” The NEED Project, National Energy Education Development, 2017,
http://www.need.org/Files/curriculum/infobook/IntroS.pdf
Using the terms provided, fill out the concept map below.
Serway, Raymond A., and Jerry S. Faughn. “Chapter 5: Work and Energy/Interactive Concept Map: Energy.” Holt McDougal Physics, Holt McDougal, a Division of
Houghton Mifflin Harcourt Publishing Co., 2012.
7
General Science 1B
Credit 3
Explain
As you complete the reading, answer the questions in the space provided.
Reading
What is the Difference Between Potential and Kinetic Energy?
An object may store energy because of its
position. The energy that is stored and ready
to be used is called potential energy
because it has the potential for moving itself
or other objects or doing work. A stretched
or compressed spring, for example, has the
potential for doing work. When a bow is
drawn back, energy is stored in the bow, as it
can do work on the arrow. A stretched
rubber band has potential energy because of
its position in a similar way.
The chemical energy in fuels is also
potential energy. The energy is contained in
the position of the atoms that compose these
substances and is released when a chemical
change takes place. Potential energy is found
in gasoline, batteries, and food.
Potential energy also relates to the gravity of an object. Heavier objects fall with more force than lighter ones,
and they gain more force the higher they fall. With this knowledge, the equation describing gravitational
potential energy makes sense.
Gravitational Potential Energy = Weight x Height
1. Where is potential energy in a car kept?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
2. Why would an airplane flying at 10,000 meters above the ground have more gravitational potential
energy than the same airplane flying at 1,000 meters above the ground?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
8
General Science 1B
Credit 3
An object in motion has its own energy due
to its movement. This energy of motion is
called kinetic energy. Moving objects have
greater force the faster they are moving and
the heavier they are. A ball moving 4 miles
per hour will not cause an impact as hard as
one moving 50 miles per hour. A freight train
will have greater impact than a toy train
moving the same speed. This is because
kinetic energy is proportional to an object’s
mass multiplied by its speed. This means
that the heavier an object is, or the faster it
moves, the more kinetic energy it has.
Adapted from Hewitt, Paul G. Conceptual Physics. Upper Saddle
River, NJ: Prentice Hall, 2006. Print.
3. Why would a baseball traveling at 20 m/s have more kinetic energy than a baseball traveling at 5 m/s?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
4. A bicycle and a semi-truck are both traveling on the same road at the same speed. Which has more
kinetic energy? Why is that?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
9
General Science 1B
Credit 3
Videos
If you would like to learn more about this topic, watch the videos below for more information. (Optional)
Potential and Kinetic Energy (6:06)

“Potential and Kinetic Energy.” YouTube. Bozeman Science, 17 Apr. 2011. Web. 01 Feb. 2016.
How are calculations done with potential and kinetic energy? This video will
explain how problems involving kinetic and gravitational potential energy can
be solved.
10
General Science 1B
Credit 3
Elaborate
Pendulum Simulation
A pendulum is a weight connected to a single point with a string or cord, allowing it to
move back and forth. Objects such as a rope swing or hanging light are examples. A
pendulum illustrates one object converting between potential and kinetic energy. At the
height of its swing, it contains potential energy that is released as it falls and speeds up,
giving it kinetic energy.
In this simulation, you will examine how a pendulum changes its energy from potential to kinetic and back
again though its movement. Open the following link to begin the simulation. Follow the directions below.
Answer the questions as you complete the simulation.
https://phet.colorado.edu/sims/html/pendulum-lab/latest/pendulum-lab_en.html
Olson, Jonathan, et al. “Pendulum Lab.” PhET, University of Colorado Boulder, 13 Sept. 2017, phet.colorado.edu/en/simulation/pendulum-lab.
Directions:
1. Select the “Energy” section of the simulation
2. Click and drag the pendulum to either side. When released it will swing by itself. Try this out, and
once you are used to how the simulation works, press the reset button (the orange circle-arrow) in
the lower right.
3. Drag the pendulum up to 45° and hold it there. Look at the graph on the left side of the screen. What
type of energy does the pendulum currently have?
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
11
General Science 1B
Credit 3
4. Release the pendulum and allow it to swing back and forth. Notice how the graph of the potential,
kinetic, and total energy changes as the pendulum swings.
5. Reset the simulation and repeat the process, but this time release the pendulum from 90°. What
differences do you notice between this and the previous trial?
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
6. On the right-hand side of the screen, use the slider labeled “Mass 1” to change the mass of the
pendulum. As you make the pendulum heavier and lighter, how does the energy of the pendulum
change?
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
Evaluate
Review Questions
Answer the following questions.
1. As the pendulum swings towards the lowest part of its swing, explain how energy is transferred.
What type of energy is it losing and gaining?
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
2. What were the differences in the pendulum’s swing speed and total energy between the 45° and the
90° swing?
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
3. What differences in the pendulum’s swing speed, motion, and energy do you notice when the
pendulum’s mass in increased?
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
4. What do you notice about the total energy (mechanical energy) at any point in the pendulum’s
swing?
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
12
General Science 1B
Credit 3
LESSON 3.2: CONSERVATION OF ENERGY
Learning Goals for this Credit
Design an investigation or model using appropriate scientific tools, resources and methods.
Use mathematics to represent physical variables and their relationships to make quantitative predictions and
to solve problems.
Learning Goals for this Lesson
 Identify situations in which conservation of mechanical energy is valid.
 Recognize the form conserved energy can take.
 Solve problems using conservation of mechanical energy.
Lesson Assignments
 Connect to Prior Knowledge
 Exploration Activity
 Reading and Questions
 Videos (optional)
 Skateboard Energy Simulation
 Review Questions
Engage
Connect to Prior Knowledge
What does it mean to “conserve money” or to “conserve resources”?
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
13
General Science 1B
Credit 3
Explore
Exploration Activity
Mechanical energy is the sum of an object’s kinetic and potential energy. This
means by simply adding these two types of energy together, the total mechanical
energy can be calculated. Energy is measured in a unit called Joules (J). Like most
measurements, it is a straightforward explanation: a larger number of Joules means a
larger amount of energy.
The image to the right depicts the amount of mechanical energy the jumper has
while falling from a building. Notice that at any point in the fall, the total amount of
energy adds up to 10,000 J, never more or less. With that in mind, answer the
following questions regarding the jumper’s total mechanical energy.
𝑴𝑬 = 𝑲𝑬 + 𝑷𝑬
ME
KE
PE
Amanda Johnson: The variables in the equations and
word problems are color coded to help you identify
them in the word problems.
Mechanical energy in joules
Kinetic energy in joules
Potential energy in joules
Use the information above to answer the following questions. Make sure to show
your work.
Amanda Johnson: beginning (at the top of the
building)
1. According to the picture, what is the initial mechanical energy of the jumper
falling from the building? What is her final mechanical energy?
2. What is the jumper’s kinetic energy when her potential energy is 2500 joules?
3. What is the jumper’s potential energy when her kinetic energy is 1000 joules?
4. If the jumper was wearing a parachute, how do you think that might affect her kinetic energy? Would
the mechanical energy of the system change? Explain your answer.
_______________________________________________________________________________________
_______________________________________________________________________________________
Adapted from Hewitt, Paul G. Conceptual Physics. Upper Saddle River, NJ: Prentice Hall, 2006. Print.
14
General Science 1B
Credit 3
Explain
As you complete the reading, answer the questions in the space provided.
Reading
What is the Law of Conservation of Energy?
More important than knowing what energy is, it is important to understand how energy behaves or transforms.
Every process or change that occurs in nature can be analyzed in terms of a transformation of energy from one
form to another. The study of various forms of energy and the transformations from one form into another led to
one of the greatest generalizations in physics, the law of conservation of energy.
The law of conservation of energy
Energy cannot be created nor destroyed. It can be transformed from
one form into another, but the total amount of energy never changes.
When you consider any system in its entirety, whether it is as simple as a swinging pendulum or as complex as
an exploding galaxy, there is one quantity that does not change: energy. It may change form or it may be
transferred from one place to another, but the total energy stays the same.
When analyzing the conservation of energy, ignore forms of energy that have a negligible influence or are not
relevant. When ignoring these forms of energy, mechanical energy is the sum of kinetic energy and all forms
of potential energy. In the absence of friction, total mechanical energy remains the same. This principle is called
conservation of mechanical energy.
Adapted from Hewitt, Paul G. Conceptual Physics. Upper Saddle River, NJ: Prentice Hall, 2006. Print.
1. In the picture above, how would the amount of kinetic energy in the third pendulum compare to the
amount of potential energy in the first and fourth pendulums?
_______________________________________________________________________________________
_______________________________________________________________________________________
15
General Science 1B
Credit 3
2. Name the two types of energy that combine to form the total mechanical energy.
_______________________________________________________________________________________
_______________________________________________________________________________________
3. How does friction affect total mechanical energy?
_______________________________________________________________________________________
_______________________________________________________________________________________
Videos
If you would like to learn more about this topic, watch the videos below for more information.
(Optional)
Law of Conservation of Energy (Roller Coaster Demo) (2:45)

“Law of Conservation of Energy (Roller Coaster Demo” YouTube. Shilpa Balaji, 12 Jan. 2014. Web.
If the total energy is always the same, what causes the roller coaster to slow
down? Roller coasters transfer electrical energy into potential, then kinetic
and frictional energies.
Conservation of Energy: Free Fall, Springs, and Pendulums
(5:18) https://www.youtube.com/watch?v=OTK9JrKC6EY
“Conservation of Energy: Free Fall, Springs, and Pendulums” YouTube. Professor Dave Explains, 13
Mar. 2017. Web.
What types of energy make up the total mechanical energy? In the absence of
external forces and friction, the total mechanical energy of a system remains
constant. The energy may only change form.
Swinging Ball of Death (2:05)

“Swinging Ball of Death.” YouTube. ProfChrisBishop, 22 Jun. 2009. Web.
Why doesn’t the ball hit the demonstrator in the face? Swinging a solid steel
ball towards one’s face might sound risky, but when done without adding
extra energy, it is actually safe.
16
General Science 1B
Credit 3
Elaborate
Skateboard Energy Simulation
To explore the conservation of energy, you will use a simulated skate park and skateboarder. The simulation
will show you how energy is transferred between kinetic (energy of movement), potential (energy of position),
and thermal (energy of heat). Open the following link to begin the simulation. Follow the directions below.
Answer the questions as you complete the simulation.
https://phet.colorado.edu/sims/html/energy-skate-park-basics/latest/energy-skate-park-basics_en.html
Paul, Ariel, et al. “Energy Skate Park: Basics.” PhET, University of Colorado BoulderA, 14 Apr. 2017, phet.colorado.edu/en/simulation/energy-skate-park-basics.
Amanda Johnson: https://phet.colorado.edu/en/simul
ation/energy-skate-park-basics Amanda Johnson:
Click on the above link to go to the Energy Simulation.
Directions Part I:
Click the “Intro” option on the first menu.
Check the “bar graph” and “speed” boxes on the right-hand side.
Drag the skateboarder to the top of one side of the ramp and let go.
Observe the simulation. What happens with the potential and kinetic energy as the skater goes back and
forth on the ramp?
_______________________________________________________________________________________
1.
2.
3.
4.
_______________________________________________________________________________________
_______________________________________________________________________________________
17
General Science 1B
Credit 3
Directions Part II:
1. Restart the simulation and choose the “playground” option.
2. Check the “bar graph” and “speed” boxes on the right-hand side.
3. Drag a piece of track from the bottom left onto the simulation. Multiple pieces can be connected end to
end on the dotted circles.
4. Create a custom track of your choosing. Let your skater go at one end and observe. Make sure that your
skater stays on the track and does not fly off of the computer screen. You may need to modify your
track until you get a version that allows the skater to move back and forth without falling off the track.
5. In the box below, sketch your track. On your sketch, label the following locations:
 PE: Where potential energy is the greatest.
 KE: Where kinetic energy is the greatest.
 PE=KE: Any points on the track where the potential energy is equal to kinetic energy.
 STOP: The spot where your skater comes to a full stop.
 TE: The area of greatest friction (where you see thermal energy increase the fastest).
18
General Science 1B
Credit 3
Evaluate
Review Questions
Answer the following questions.
1. As the skater moves down one side of the ramp, what happens to the potential and kinetic energy?
_______________________________________________________________________________________
_______________________________________________________________________________________
2. When the skater comes to a stop at the top of either side of the ramp, what happens to the potential and
kinetic energy?
_______________________________________________________________________________________
_______________________________________________________________________________________
3. How much potential energy does the skater have when her speed is at its fastest?
_______________________________________________________________________________________
_______________________________________________________________________________________
4. The “total” energy bar is the sum of the potential and kinetic energies. What happens to it as the skater
moves up and down the ramp?
_______________________________________________________________________________________
_______________________________________________________________________________________
19
General Science 1B
Credit 3
LESSON 3.3: MACHINES
Learning Goals for this Credit
Design an investigation or model using appropriate scientific tools, resources and methods.
Use mathematics to represent physical variables and their relationships to make quantitative predictions and
to solve problems.
Learning Goals for this Lesson
 Identify the six different types of simple machines.
 Describe energy transfer within a machine.
 Explain a machines ability to conserve energy.
Lesson Assignments
 Connect to Prior Knowledge
 Exploration Activity
 Reading and Questions
 Videos (optional)
 Energy Transfer in a Trebuchet
 Review Questions
Engage
Connect to Prior Knowledge
What is an example of a machine you have used recently? What
task did it help you accomplish?
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
20
General Science 1B
Credit 3
Explore
Exploration Activity
A machine is a device that is used to increase or to change direction of forces. This is accomplished through the
conservation of energy. For example, an automobile is transferring energy stored in gasoline or a battery into
kinetic energy that moves it forward. While some machines may seem to have endless complexity, they can
typically be broken down in to very simple parts. In the classic definition, there are six types of simple
machines.


Wedge: A device that forces things
apart.
Wheel and axle: Used to reduce
friction.
Lever: Moves around a pivot point to
increase or decrease mechanical
advantage.
Inclined plane: Raises objects by
moving up a slope.
Screw: A device that can lift or hold
things together.
Pulley: Changes the direction of a force.




Look around and find as many simple machines as you can. Look closely; they are everywhere! When you find
a simple machine, write it down in the correct category in the table below. If you find a compound machine
(one that combines more than one simple machine), record it in the compound machine row. Make sure to list
at least one example for each type of simple machine.
Simple Machine Type
Examples
Inclined plane
Pulley
Wedge
Lever
Screw
Wheel and axle
Compound machine
21
General Science 1B
Credit 3
Explain
As you complete the reading, answer the questions in the space provided.
Reading
What are Rube Goldberg Machines?
A Rube Goldberg machine is an over-engineered device that
contains a series of events in a chain reaction to perform a simple
task. While they are unnecessarily complicated and are designed for
amusement only, they do utilize many simple machines performing
together to achieve a desired outcome. By breaking down each step,
you can get an idea of how many complicated machines work.
1. What simple machines can you identify in the “Self
Operating Napkin” illustration on the right?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
The Rube Goldberg machine below has a total of 15 different steps that use a combination of simple machines.
The table on the next page explains what is happening in each step.
22
General Science 1B
Credit 3
Step
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Explanation
Windup robot toy is released. Toy moves rightward across platform, knocking the ball off the
platform.
The ball rolls off of the platform and falls into cup A. This upsets the balance of the Atwood Machine,
causing cup A to accelerate downward while cup B accelerates upward.
Cup B knocks the left side of the lever upwards. The lifting up of the left side of the lever causes a
steel marble to roll downwards into the set of marble tracks.
The marble zigzags down the angled tracks. During the first section, the marble rolls through a set of
chimes of varying length. After the last ramp, the steel marble collides with a lighter steel ball.
The ball rolls from the angled tracks into a funnel where it falls onto the trigger of a mousetrap.
The mousetrap goes off, with its metal arm swinging from left to right.
The clothespin is squeezed open by the swinging arm of the mousetrap, releasing a string.
The released string causes the weight on the opposite side of the pulley system to accelerate
downwards.
The downward accelerating mass collides with the arm of a rotating lever. The bottom lever spins
counter-clockwise, knocking into the arm of the lever above it. The levers continue to spin,
transferring the energy upward to the top lever.
The top lever swings into a domino, beginning another chain of falling dominoes. The final domino
collides with a ball from a Newton’s Cradle toy that sits perched on the platform with the dominoes.
The first ball of the Newton’s Cradle swings into the other four balls. The rightmost ball swings
forward, knocking into a domino on the adjacent platform where they initiate another chain of
domino collisions, eventually knocking into a marble.
The marble rolls down through the curved tubing into the left compartment of a lever.
The weight of the marble causes the left side of the lever to move. The upward motion of the right side
of the lever lifts the rod that supports the platform above.
The left side of the platform lifts upwards, causing the car to roll downwards from left to right,
eventually falling into a cup that is attached to a string and pulley system.
The car falling into the cup causes the cup to accelerate downwards. The string on the opposite side
of the pulleys moves upwards, raising the flag and finishing the machine.
Rube Goldberg Machines: An inquiry-based STEM Approach. Michael Harms. 2011
1. Which type of simple machines are being used in this Rube Goldberg device?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
2. Identify a step in which potential energy is transferred into kinetic enery. Explain how this transfer of
energy is taking place.
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
23
General Science 1B
Credit 3
Videos
If you would like to learn more about this topic, watch the videos below for more information. (Optional)
Energy Transfer in a Trebuchet (4:18)
http://ca.pbslearningmedia.org/resource/hew06.sci.phys.maf.trebuchet/energytransfer-in-a-trebuchet/
“Energy Transfer in a Trebuchet.” PBS LearningMedia. NOVA, 2007. Web. 08 Feb. 2016.
How is potential energy converted into kinetic energy in a trebuchet?
In this video historians, engineers, and trade experts recreate a medieval throwing
machine called a trebuchet to launch a projectile.
Amazing Rube Goldberg Machine (3:26)

“amazing rube goldberg machine.” YouTube. rubegoldbergs, 1 Nov. 2007. Web
How many different simple machine can you identify? This video gives an
example of a very complex and elaborate Rube Goldberg machine.
Marble Roller Coaster (2:11)

“Archimedes in HD.” YouTube. Mark S, 22 Jan. 2012. Web
Pay special attention to how the marbles climb to the top. What kind of simple
machine is that, and how is it used? This marble rollercoaster utilizes the same
physics principles as a theme park ride.
Simple Machines (7:21)

“Simple Machines – English” YouTube. Aarchemides – The fun side of science, 25 Feb 2014. Web.
How do simple machines work? This video gives a thorough explanation of each
type of simple machine with examples.
24
General Science 1B
Credit 3
Elaborate
Energy Transfer in a Trebuchet
In medieval times, one of the most fearsome weapons was a trebuchet—a powerful machine used to hurl
projectiles. Combining the launching capabilities of a catapult and a sling, trebuchets were able to throw
massive objects at high speeds and over great distances. Trebuchets were also more accurate than a basic
catapult and more powerful than a simple sling; they could throw objects hundreds of pounds in weight to
targets hundreds of yards away. During a siege, a trebuchet could be used to crumble castle walls by launching
large rocks or to spread disease to the people inside the castle walls by tossing over dead animals.
Imagine what would happen on a seesaw
(a simple lever) if a book were placed on
one end and you were to jump on the
other end—the book would go flying into
the air. A trebuchet functions similarly,
except that the pivot point of the lever is
placed off-center (in this case, farther
away from the load) to amplify the force
that launches the projectile. The load, or
object to be moved, is placed in a sling
(composed of a pouch and two cords)
attached to the long arm of the lever. A
very heavy counterweight is attached to
the short arm of the lever. When the
counterweight falls, the long arm of the lever is raised very quickly into the air, pulling the sling up with it. As
the sling swings into a vertical position, one end of the sling is unleashed, opening up the sling and releasing the
load at a high velocity.
To put a trebuchet into its “cocked” position, a team of people use their energy to hoist the counterweight. When
the counterweight is raised, it gains this energy as potential energy. In this case, the potential energy is
gravitational potential energy—energy that results from the position of an object in a gravitational field. The
amount of gravitational potential energy is dependent on both the weight of the object and its position, or
height, above the ground. Since the counterweight in a trebuchet is very heavy, it has a great deal of potential
energy.
While energy cannot be created or destroyed, it can change forms. The potential energy from the raised
counterweight is transformed into kinetic energy—the energy of motion—as the counterweight is released and
begins to fall. The downward motion of the counterweight then causes the sling to swing and the projectile to be
released. The potential energy that was stored in the raised counterweight is transferred, in the form of kinetic
energy, to the projectile, which is released at a high velocity.
1. Where does the potential energy in the lever arm come from?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
25
General Science 1B
Credit 3
2. Where is there potential energy once the trebuchet is loaded and cocked, before it is released?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
3. Where is there kinetic energy once the trebuchet is released?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
4. What evidence is there that energy is conserved?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
26
General Science 1B
Credit 3
Evaluate
Review Questions
Answer the following questions.
1. What is a simple machine?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
2. What is a compound machine?
_______________________________________________________________________________________
_______________________________________________________________________________________
______________________________________________________________________________________
3. A trebuchet is a compound machine. Identify the simple machines that in a trebuchet.
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
Revisit the essential question. Did your answer change? Why or why not?
Essential Question
What are some examples of energy you can detect in the room you are in right now?
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
27
General Science 1B
Credit 3